Fractional IMC-PID-filter controllers design for non integer order systems

Fractional order controller design with a small number of tuning parameters is very attractive. Few attempts have been done recently for some limited cases of models. In this paper, a new approach is developed to design simple fractional-order controllers to handle fractional order processes. The fractional property is not especially imposed by the controller structure but by the closed-loop reference model. The resulting controller is fractional but it has a very interesting structure for its implementation. Indeed, the controller can be decomposed into two transfer functions: a (PID mu)-D-upsilon-controller and a simple fractional filter. The new structure is named (PID mu)-D-upsilon-FOF-controller. The design method is based on the internal model control (IMC) paradigm. (C) 2014 Elsevier Ltd. All rights reserved.